Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/61—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups
  • C07C45/64—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by reactions not involving the formation of >C = O groups by introduction of functional groups containing oxygen only in singly bound form

Definitions

• This invention relates to a process for producing p-hydroxybenzaldehyde and more particularly it relates to a process for producing p-hydroxybenzaldehyde by reacting p-nitrotoluene with sodium polysulphide to obtain p-aminobenzaldehyde, diazotizing the thus obtained p-aminobenzaldehyde and hydrolyzing the diazotized p-aminobenzaldehyde to produce the p-hydroxybenzaldehyde.
• P-hydroxybenzaldehyde is useful as an intermediate material for medicines, agricultural chemicals, perfumery and is in increasing demand year by year.
• processes such as a Reimer-Tiemann process disclosed in U.S. Pat. No. 3,365,500 and a phosphoric acid ester process described in Japanese Patent Gazette No. 3828/73.
• the former process comprises reacting phenol with chloroform in the presence of an alkali to produce salicylaldehyde and p-hydroxybenzaldehyde; however, the amount of p-hydroxybenzaldehyde so produced is within the range of as small as 20-25% of the total weight of said two aldehydes and the yield thereof is within the range of 15-20% at highest based on the amount of phenol used because the main product contained in the reaction mixture is salicylaldehyde.
• the latter process comprises chlorinating tri-p-cresylphosphate in the presence of an azobis type catalyst such as azobis isobutyronitrile and hydrolyzing the thus chlorinated compound to produce p-hydroxybenzaldehyde;
• an azobis type catalyst such as azobis isobutyronitrile
• this known process is disadvantageous in that tri-p-cresylphosphate as the starting material is an awkward compound to handle industrially because it is solid at ambient temperature and that said chlorinated compound takes a long time to be hydrolyzed because of its low hydrolyzability.
• Diazotization or diazo-reactions in general, are illustrated in, for example, Experimental Organic Chemistry (third revised edition) written by S. Yamaguchi and published in 1934 by Nankodo Bookstore, Japan, the publication describing on page 339 thereof a process for the synthesis of guaiacol from o-anisidine by dissolving o-anisidine in iced water and sulphuric acid to form a solution, adding sodium nitrite to the thus formed solution for diazotization of the o-anisidine and then hydrolyzing the diazotized compound in a mixed liquid, at 135°-140° C., of conc. sulphuric acid and anhydrous sodium sulphate to obtain guaiacol.
• P-aminobenzaldehyde which may be used as a starting material for p-hydroxybenzaldehyde, is a compound which is thermally unstable in an acidic medium. It is easily condensed to form a Schiff's base as indicated in the following reaction formula: ##STR1##
• n is an integer of one or more.
• An object of this invention is to provide a process for producing p-aminobenzaldehyde in a good yield from p-nitrotoluene.
• This process comprises reacting p-nitrotoluene with sodium polysulphide (Na 2 Sx) prepared by reacting sodium hydroxide with hydrogen sulphide to form sodium hydrosulphide and incorporating the thus formed sodium hydrosulphide with sodium hydroxide and then with sulphur.
• Na 2 Sx sodium polysulphide
• Another object of this invention is to provide a process for producing p-hydroxybenzaldehyde stably, substantially stoichiometrically and without producing tarry materials at the time of hydrolysis, from p-aminobenzaldehyde which is thermally unstable in an acidic medium.
• intensive studies were made by the present inventors to find the optimum reaction time and temperature used in the conversion of p-aminobenzaldehyde to the sulphate thereof by the addition of sulphuric acid and also to find the optimum temperature range used in the hydrolysis of the diazonium salt when producing p-hydroxybenzaldehyde from p-aminobenzaldehyde, after which the optimum reaction conditions have been found.
• this process comprises adding p-aminobenzaldehyde to an aqueous solution (preferably 2-50 wt.%) of sulphuric acid at a specified temperature of 60°-100° C., preferably 75°-90° C., to form the sulphate thereof as rapidly as possible and hydrolyzing, after cooling, the thus formed sulphate with water or an aqueous solution (preferably, less than 70 wt.% concentration) of sulphuric acid at a specified temperature of 70°-100° C. to obtain p-hydroxybenzaldehyde under the advantageous conditions as mentioned above.
• an aqueous solution preferably 2-50 wt.% of sulphuric acid at a specified temperature of 60°-100° C., preferably 75°-90° C.
• Still another object of this invention is to provide a novel process for producing p-hydroxybenzaldehyde through p-aminobenzaldehyde from p-nitrotoluene.
• This process comprises reacting p-nitrotoluene with sodium polysulphide prepared by reacting sodium hydroxide with hydrogen sulphide and incorporating the resulting sodium hydrosulphide with sodium hydroxide and then with sulphur, in the presence or absence of an aprotic polar compound in a mixed solvent consisting of an alcohol and an aqueous alkali solution to produce p-aminobenzaldehyde, adding the thus produced p-aminobenzaldehyde to an aqueous solution, preferably a 2-50 wt.% aqueous solution of sulphuric acid at 60°-100° C., preferably 75°-90° C., to produce the sulphate thereof rapidly, diazotizing (after cooling) the thus produced sulphate to obtain a di
• the sodium polysulphide may preferably be a specific one which is prepared by reacting sodium hydroxide in aqueous solution with hydrogen sulphide to produce sodium hydrosulphide, adding sodium hydroxide to the thus produced sodium hydrosulphide to produce sodium sulphide and then adding sulphur to the sodium sulphide so produced, however, the sodium polysulphide does not have to be limited to the aforesaid specific one.
• the alcohol and the aqueous alkali solution be present in a ratio by weight of 0.1-2:1 in said mixed solvent, that the aqueous alkali solution contains an alkali in a concentration of 1-50% by weight thereof and that the mixed solvent be used in an amount of 4-100 parts by weight per part by weight of p-nitrotoluene.
• concentration of the aqueous solution of sodium hydroxide to be reacted hydrogen sulphide is preferably in the range of 1-30% by weight.
• p-nitrotoluene be reacted with sodium polysulphide in a molar ratio of 2-8:1 at a temperature of 50°-120° C. for a time sufficient to produce p-aminobenzaldehyde.
• the alcohols which may be used in this invention include methanol, ethanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and mixtures thereof, among which alcoholic mixtures containing at least 80% by weight of ethanol (with the remainder being another alcohol, water or the like, or a mixture thereof) are preferred for increasing the yield of p-aminobenzaldehyde to be obtained.
• the aprotic polar compounds used herein include N,N-dimethylformamide, N,N-diethylformamide, N,N-diphenylformamide, dimethylsulfoxide, tris(trimethylamino) phosphate, tetrahydrofuran, acetonitrile and other polar compounds which will not liberate H + therefrom.
• the use of the aprotic polar compound in an amount of 0.01-10% by weight of p-nitrotoluene will result in producing p-aminobenzaldehyde in a remarkably increased yield.
• N,N-dimethylformamide is particularly preferred.
• the temperature at which hydrogen sulphide is reacted with sodium hydroxide in aqueous solution is not particularly limited, but it may preferably be a comparatively low temperature which is in the range of 10°-60° C.
• the use of lower temperatures will make the reaction prolonged, while the use of higher temperatures will decrease the reaction efficiency of the hydrogen sulphide.
• sodium hydroxide be added to the sodium hydrosulphide obtained in a molar ratio of from 1.0 to 3.0 to produce sodium sulphide.
• the addition of sodium hydroxide in a molar ratio of less than 1.0 will result in producing p-aminobenzaldehyde in a low yield, while the addition thereof in a molar ratio of more than 3.0 will not result in increasing the yield to an appreciable extent, this being economically disadvantageous.
• sodium polysulphide in the production of sodium polysulphide according to this invention by the addition of sulphur, it is desirable that sulphur be added in such an amount as to produce a sodium polysulphide represented by the formula Na 2 Sx wherein x is an integer of from 2 to 5. If sulphur be not added in such an amount as mentioned above, then by-products will be produced in large amounts and the desired product obtained in a decreased yield.
• sodium polysulphide according to this invention is reacted with p-nitrotoluene in a mixed solvent consisting of an aqueous alkali solution and an alcoholic mixture containing at least 80% by weight of ethanol, then p-aminobenzaldehyde will be obtained in a good yield.
• the sulphate of p-aminobenzaldehyde obtained at the lower reaction temperature will give p-hydroxybenzaldehyde in a low yield while that obtained at the higher reaction temperature will disadvantageously give a low yield, accompanied with the formation of tarry materials.
• a sulphuric acid solution and p-aminobenzaldehyde added thereto are reacted together at 60°-100° C., preferably 75°-90° C., under agitation for 10-30 minutes.
• the sulphuric acid concentration of the solution is not particularly limited, but it is preferably in the range of usually 2-50% by weight.
• the sulphate of p-aminobenzaldehyde so obtained is immediately cooled (to a low temperature such as 10° to 0° C.) by cooled or iced water and then diazotized with a usual diazotizing agent such as an aqueous solution of sodium nitrite while adding the agent dropwise to the sulphate so cooled. It is effective or preferable in this case to add to the thus diazotized compound a decomposing agent, such as sulfamic acid or urea, in such an amount necessary for decomposing an excess of the sodium nitrite added.
• a decomposing agent such as sulfamic acid or urea
• the diazotizing agents used herein may include sodium nitrite, potassium nitrite, ammonium nitrite and nitrosyl sulphuric acid, and they may be used in a concentration of 5-50% by weight at lower than 10° C. in the diazotization.
• the diazonium salt of p-aminobenzaldehyde may preferably be hydrolyzed at a temperature in the range of from 70° to 100° C.; if the hydrolysis be effected at a temperature above 100° C. then tarry materials will be produced, while if it be effected at a temperature below 70° C. then it will not proceed smoothly. Therefore, it is necessary in the practice of this invention to carry out the hydrolysis at a temperature ranging from 70° to 100° C. in water or an aqueous solution of sulphuric acid.
• a solution of 5 g (0.125 mol) of sodium hydroxide in 10 g of water was introduced into a 100-ml flask, maintained at 45° C. and then reacted with 4.1 g (0.121 mol) of hydrogen sulphide by passing it through the solution for one hour, to obtain an aqueous solution of sodium hydrosulphide.
• the aqueous solution of sodium hydrosulphide so obtained was introduced into a 1-liter flask and incorporated with 9.1 g (0.228 mol) of sodium hydroxide and 547 g of water to produce an aqueous solution of sodium sulphide.
• the aqueous solution of sodium sulphide so produced was incorporated with 14.5 g (0.45 mol) and reacted together at 80° C. for one hour to produce an aqueous solution of sodium polysulphide which was represented by the formula Na 2 Sx wherein x is a value of 3.24.
• the resulting reaction mixture was subjected to steam distillation to obtain 42.3 g (0.350 mol) of p-aminobenzaldehyde in purified form.
• the yield of the p-aminobenzaldehyde so obtained was 71.8%, based on the weight of p-nitrotoluene used.
• the reaction mixture so cooled was incorporated dropwise over a time period of 30 minutes with a solution of 28.2 g (0.41 mol) of sodium nitrite in 79.3 g of water while maintaining the solution at a temperature of lower than 5° C., incorporated with 2.6 g (0.06 mol) of urea to decompose an excess of the sodium nitrite used and further incorporated with 529 g of iced water for dilution thereby obtaining 1132 g of an aqueous solution of a diazonium salt of p-aminobenzaldehyde.
• aqueous solution of the diazonium salt maintained at lower than 5° C. was added dropwise over a period of time of 30 minutes to 767 g of a 20% aqueous solution of sulphuric acid heated to 80° C. and, soon after the end of the addition, heated rapidly to 90° C. to complete the hydrolysis of the diazonium salt thereby obtaining 43.2 g (0.354 mol) of p-hydroxybenzaldehyde.
• the yield of the thus obtained p-hydroxybenzaldehyde was substantially stoichiometric with respect to the amount of p-aminobenzaldehyde used and was therefore 71.8%, based on the weight of p-nitrotoluene used.
• Example 1 The procedure of Example 1 was followed except that 2.3 g (3.4 wt.% of the p-nitrotoluene) of acetonitrile were substituted for the N,N-dimethylformamide, to obtain 37.7 g (0.312 mol) of p-aminobenzaldehyde and then obtain 38.5 g (0.315 mol) of p-hydroxybenzaldehyde.
• the yield of the thus obtained p-hydroxyaldehyde was 64.8%, based on the weight of p-nitrotoluene used.
• Example 1 The procedure of Example 1 was followed except that 3.2 g (4.8% by weight of the p-nitrotoluene) of dimethylsulfoxide were substituted for the N,N-dimethylformamide, to obtain 38.3 g (0.317 mol) of p-aminobenzaldehyde and then 39.1 g (0.320 mol) of p-hydroxybenzaldehyde.
• the yield of the p-hydroxybenzaldehyde was 65.8%, based on the weight of p-nitrotoluene used.
• the aqueous alkali solution so formed was added dropwise over a period of time of 2 hours to a solution of 50 g (0.36 mol) of p-nitrotoluene in a mixture of 232 g of ethanol and 4.2 g (8.4% by weight of the p-nitrotoluene) of N,N-dimethylformamide while maintaining said solution at 82° C.
• the whole mass was refluxed for an additional two hours to complete the reaction thereby producing p-aminobenzaldehyde.
• the amount of the p-aminobenzaldehyde so produced was 27.9 g (0.23 mol) and the yield thereof was 64%, based on the weight of p-nitrotoluene used.
• the p-aminobenzaldehyde so produced was diazotized and hydrolyzed in the same manner as in Example 1 to obtain 28.9 g (0.23 mol) of p-hydroxybenzaldehyde. The yield of this final product was 64%, based on the weight of p-nitrotoluene used.
• Example 1 The procedure of Example 1 was followed except that the N,N-dimethylformamide was not added, to obtain p-hydroxybenzaldehyde.
• the yield of the p-hydroxybenzaldehyde was 56%, based on the weight of p-nitrotoluene used.
• Example 4 The procedure of Example 4 was followed except that the N,N-dimethylformamide was not added, to obtain p-hydroxybenzaldehyde in a yield of 40%, based on the weight of p-nitrotoluene used.
• Example 2 The procedure of Example 1 was repeated except that the N,N-dimethylformamide was not added and p-aminobenzaldehyde was reacted with sulphuric acid in 40% aqueous solution at 40° C. for one hour, to obtain p-hydroxybenzaldehyde in a yield of 23%, based on the weight of p-nitrotoluene used.
• a solution of 14 g (0.35 mol) of sodium hydroxide in 28 g of water was introduced into a 100-ml flask where the solution was maintained at 45° C. and reacted with 10.6 g (0.31 mol) of hydrogen sulphide by passing it through said solution for one hour to obtain 52.6 g of an aqueous solution of sodium hydrosulphide.
• the sodium hydrosulphide solution so obtained was introduced into a 2-liter flask where it was incorporated with 22 g (0.55 mol) of sodium hydroxide and 1435 g of water to obtain 1509.6 g of an aqueous solution of sodium sulphide.
• the aqueous solution of sodium sulphide so obtained was incorporated with 37.4 g (1.17 mol) of sulphur to react the sulphide with sulphur at 80° C. for one hour thereby obtaining 1547 g of an aqueous solution of sodium polysulphide which could be represented by the formula Na 2 Sx wherein x is 3.29.
• the aqueous solution of sodium polysulphide so obtained was incorporated with 135 g of a 50% aqueous solution of sodium hydroxide to render the former alkaline.
• the reaction mixture was subjected to steam distillation to distil off the ethanol and p-toluidine, and the p-aminobenzaldehyde was crystallized and filtered out to obtain 86 g (0.71 mol) of p-aminobenzaldehyde in crystal form.
• the yield of p-aminobenzaldehyde so obtained was 56%, based on the weight of p-nitrotoluene obtained.
• Example 5 The procedure of Example 5 was followed except that 23.5 g (0.59 mol) of sodium hydrosulphide were added to the aqueous solution of sodium hydrosulphide obtained, to obtain 92.9 g (0.77 mol) of p-aminobenzaldehyde in a yield of 60% of p-nitrotoluene used.
• Example 6 The procedure of Example 6 was followed except that a modified ethanol containing 10% of methanol was substituted for the ethanol, to obtain 88.3 g (0.73 mol) of p-aminobenzaldehyde.
• the yield of p-aminobenzaldehyde so obtained was 57%, based on the weight of p-nitrotoluene used.
• This sodium polysulphide was such that it was represented by the formula Na 2 Sx wherein x was 4.5.
• the sodium polysulphide in aqueous solution so obtained was incorporated with 27 g of sodium hydroxide to obtain an alkaline aqueous solution which was added dropwise at 82° C.
• reaction mixture thus obtained was subjected to high-speed liquid chromatography and found to contain 18.3 g (0.15 mol) of p-aminobenzaldehyde and 3.9 g (0.036 mol) of p-toluidine.
• the reaction mixture was subjected to steam distillation to distil off the ethanol and the p-toluidine, and then the p-aminobenzaldehyde was crystallized and filtered out thereby obtaining 17.4 g (0.14 mol) of crystals thereof.
• the yield of p-amonibenzaldehyde so obtained was 40%, based on the weight of p-nitrotoluene used.
• Example 5 The procedure of Example 5 was followed except that 8 g (0.2 mol) of sodium hydroxide were added to the 52.6 g of the aqueous solution of sodium hydrosulphide, to obtain 69.7 g (0.576 mol) of p-aminobenzaldehyde which was represented by the formula Na 2 Sx wherein x is 5.38.
• the yield of p-aminobenzaldehyde so obtained was 45%, based on the weight of p-nitrotoluene used.
• the mixture so formed was heated to 80° C., reacted together under agitation at this temperature for 15 minutes, incorporated with 18 g of iced water to cool the resulting reaction mixture rapidly, incorporated dropwise over a time period of 30 minutes with a solution of 3.2 g (0.047 mol) of sodium nitrite in 9 g of water while maintaining the solution at a temperature below 5° C., incorporated with 0.3 g (0.005 mol) of urea to decompose an excess of the sodium nitrite and then incorporated with 60 g of iced water for dilution thereby to obtain 128.5 g of an aqueous solution of a diazonium salt of p-aminobenzaldehyde.
• the thus obtained diazonium salt solution maintained at a temperature below 5° C. was added over a period of time of 30 minutes to 87 g of a 20% aqueous solution of sulphuric acid heated to 80° C., after which the whole mass was heated rapidly to 90° C. to complete the hydrolysis of the diazonium salt.
• Example 8 The procedure of Example 8 was followed except that 87 g of water were used in substitution for the 20% aqueous solution of sulphuric acid as the decomposing liquid, to obtain 4.5 g (0.037 mol) of p-hydroxybenzaldehyde. The yield thereof was 92%, based on the weight of p-aminobenzaldehyde used.
• Example 8 The procedure of Example 8 was followed except that the production of the sulphate of p-aminobenzaldehyde by reaction with sulphuric acid in 40% aqueous solution was effected at 40° C. for one hour, to obtain 2.0 g (0.016 mol) of p-hydroxybenzaldehyde. The yield thereof was 41%, based on the weight of p-aminobenzaldehyde used.
• Example 8 The procedure of Example 8 was followed except that the reaction of p-aminobenzaldehyde with sulphuric acid in 40% aqueous solution was effected at 120° C. for 15 minutes, to obtain 2.6 g (0.021 mol) of p-hydroxybenzaldehyde, accompanied with formation of tarry materials in large quantities.
• the yield of p-hydroxybenzaldehyde so obtained was 53%, based on the weight of p-aminobenzaldehyde used.
• Example 8 The procedure of Example 8 was followed except that a mixture of 15 g of sodium sulphate with 30 g of a 67% aqueous solution of sulphuric acid was substituted for the 20% aqueous solution of sulphuric acid as the decomposing liquid and that a hydrolyzing temperature of 130° C. was used, to obtain 2.0 g (0.016 mol) of p-hydroxybenzaldehyde.
• the yield of p-hydroxybenzaldehyde so obtained was 42%, based on the weight of p-aminobenzaldehyde, and, in this case, tarry materials were produced in large quantities.

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